Browsing by Author "Tepper, Angeles"

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    Country-level gender inequality is associated with structural differences in the brains of women and men
    (National Academy of Sciences, 2023) Zugman, Andrés; Alliende, Luz María; Medel Sierralta, Vicente Nicolás; Bethlehem, Richard A. I.; Seidlitz, Jakob; Ringlein, Grace; Arango, Celso; Arnatkeviciutė, Aurina; Asmal, Laila; Bellgrove, Mark; Benegal, Vivek; Bernardo, Miquel; Billeke, Pablo; Bosch-Bayard, Jorge; Bressan, Rodrigo; Busatto, Geraldo F.; Castro, Mariana N.; Chaim-Avancini, Tiffany; Compte, Albert; Costanzi, Monise; Czepielewski, Leticia; Dazzan, Paola; Fuente-Sandoval, Camilo de la; Forti, Marta di; Díaz-Caneja, Covadonga M.; Díaz-Zuluaga, Ana María; Plessis, Stefan du; Duran, Fabio L. S.; Fittipaldi, Sol; Fornito, Alex; Freimer, Nelson B.; Gadelha, Ary; Gama, Clarissa S.; Garani, Ranjini; García-Rizo, Clemente; González Campo, Cecilia; González-Valderrama, Alfonso; Guinjoan, Salvador; Holla, Bharath; Ibáñez, Agustín; Jackowski, Andrea; Ivanovic, Daniza; León-Ortiz, Pablo; Lochner, Christine; López Jaramillo, Carlos; Luckhoff, Hilmar; Massuda, Raffael; McGuire, Philip; Miyata, Jun; Mizrahi, Romina; Murray, Robin; Ozerdem, Aysegul; Pan, Pedro M.; Parellada, Mara; Phahladira, Lebogan; Ramírez Mahaluf, Juan P.; Reckziegel, Ramiro; Marques Tiago Reis; Reyes-Madrigal, Francisco; Roos, Annerine; Rosa, Pedro; Salum, Giovanni; Scheffler, Freda; Schumann, Gunter; Serpa, Mauricio; Stein, Dan J.; Tepper, Angeles; Tiego, Jeggan; Ueno, Tsukasa; Undurraga, Juan; Undurraga, Eduardo A.; Valdés-Sosa, Pedro; Valli, Isabel; Villarreal, Mirta; Winton-Brown, Toby T.; Yalin, Nefize; Zamorano, Francisco; Zanetti, Marcus V.; Veda, C.; Winkler, Anderson M.; Pine, Daniel S.; Evans-Lacko, Sara; Crossley Karmelic, Nicolas Andrés
    Gender inequality across the world has been associated with a higher risk to mental health problems and lower academic achievement in women compared to men. We also know that the brain is shaped by nurturing and adverse socio-environmental experiences. Therefore, unequal exposure to harsher conditions for women compared to men in gender-unequal countries might be reflected in differences in their brain structure, and this could be the neural mechanism partly explaining women’s worse outcomes in gender-unequal countries. We examined this through a random-effects meta-analysis on cortical thickness and surface area differences between adult healthy men and women, including a meta-regression in which country-level gender inequality acted as an explanatory variable for the observed differences. A total of 139 samples from 29 different countries, totaling 7,876 MRI scans, were included. Thickness of the right hemisphere, and particularly the right caudal anterior cingulate, right medial orbitofrontal, and left lateral occipital cortex, presented no differences or even thicker regional cortices in women compared to men in gender-equal countries, reversing to thinner cortices in countries with greater gender inequality. These results point to the potentially hazardous effect of gender inequality on women’s brains and provide initial evidence for neuroscience-informed policies for gender equality.
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    Dysconnectivity in Schizophrenia Revisited: Abnormal Temporal Organization of Dynamic Functional Connectivity in Patients With a First Episode of Psychosis
    (2023) Ramirez-Mahaluf, Juan P.; Tepper, Angeles; Maria Alliende, Luz; Mena, Carlos; Castaneda, Carmen Paz; Iruretagoyena, Barbara; Nachar, Ruben; Reyes-Madrigal, Francisco; Leon-Ortiz, Pablo; Mora-Duran, Ricardo; Ossandon, Tomas; Gonzalez-Valderrama, Alfonso; Undurraga, Juan; De la Fuente-Sandoval, Camilo; Crossley, Nicolas A.
    Background and Hypothesis Abnormal functional connectivity between brain regions is a consistent finding in schizophrenia, including functional magnetic resonance imaging (fMRI) studies. Recent studies have highlighted that connectivity changes in time in healthy subjects. We here examined the temporal changes in functional connectivity in patients with a first episode of psychosis (FEP). Specifically, we analyzed the temporal order in which whole-brain organization states were visited. Study Design Two case-control studies, including in each sample a subgroup scanned a second time after treatment. Chilean sample included 79 patients with a FEP and 83 healthy controls. Mexican sample included 21 antipsychotic-naive FEP patients and 15 healthy controls. Characteristics of the temporal trajectories between whole-brain functional connectivity meta-states were examined via resting-state functional MRI using elements of network science. We compared the cohorts of cases and controls and explored their differences as well as potential associations with symptoms, cognition, and antipsychotic medication doses. Study Results We found that the temporal sequence in which patients' brain dynamics visited the different states was more redundant and segregated. Patients were less flexible than controls in changing their network in time from different configurations, and explored the whole landscape of possible states in a less efficient way. These changes were related to the dose of antipsychotics the patients were receiving. We replicated the relationship with antipsychotic medication in the antipsychotic-naive FEP sample scanned before and after treatment. Conclusions We conclude that psychosis is related to a temporal disorganization of the brain's dynamic functional connectivity, and this is associated with antipsychotic medication use.
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    Functional Dysconnectivity in Ventral Striatocortical Systems in 22q11.2 Deletion Syndrome
    (OXFORD UNIV PRESS, 2021) Tepper, Angeles; Cuiza Vasquez Analia; Alliende, Luz María; Mena, Carlos; Ramirez Mahaluf, Juan Pablo; Iruretagoyena, Barbara; Ornstein, Claudia; Fritsch, Rosemarie; Nachar, Ruben; Gonzalez Valderrama, Alfonso; Undurraga, Juan; Pablo Cruz, Juan; Tejos, Cristian; Fornito, Alex; Repetto, Gabriela; Crossley, Nicolas
    22q11.2 deletion syndrome (22q11.2DS) is a genetic neurodevelopmental disorder that represents one of the greatest known risk factors for psychosis. Previous studies in psychotic subjects without the deletion have identified a dopaminergic dysfunction in striatal regions, and dysconnectivity of striatocortical systems, as an important mechanism in the emergence of psychosis. Here, we used resting-state functional MRI to examine striatocortical functional connectivity in 22q11.2DS patients. We used a 2 x 2 factorial design including 125 subjects (55 healthy controls, 28 22q11.2DS patients without a history of psychosis, 10 22q11.2DS patients with a history of psychosis, and 32 subjects with a history of psychosis without the deletion), allowing us to identify network effects related to the deletion and to the presence of psychosis. In line with previous results from psychotic patients without 22q11.2DS, we found that there was a dorsal to ventral gradient of hypo- to hyperstriatocortical connectivity related to psychosis across both patient groups. The 22q11.2DS was additionally associated with abnormal functional connectivity in ventral striatocortical networks, with no significant differences identified in the dorsal system. Abnormalities in the ventral striatocortical system observed in these individuals with high genetic risk to psychosis may thus reflect a marker of illness risk.
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    Quantitative Susceptibility Mapping MRI in Deep-Brain Nuclei in First-Episode Psychosis
    (2023) García Saborit, Marisleydis; Jara Vallejos, Alejandro Antonio; Muñoz Camelo, Néstor Andrés; Milovic, Carlos; Tepper, Angeles; Alliende Correa, Luz María; Mena, Carlos; Iruretagoyena Bruce, Bárbara Arantzazu; Ramírez Mahaluf, Juan Pablo; Diaz, Camila; Nachar, Rubén; Castaneda, Carmen Paz; Gonzalez, Alfonso; Undurraga, Juan; Crossley, Nicolás; Tejos Núñez, Cristián Andrés
    Background Psychosis is related to neurochemical changes in deep-brain nuclei, particularly suggesting dopamine dysfunctions. We used an magnetic resonance imaging-based technique called quantitative susceptibility mapping (QSM) to study these regions in psychosis. QSM quantifies magnetic susceptibility in the brain, which is associated with iron concentrations. Since iron is a cofactor in dopamine pathways and co-localizes with inhibitory neurons, differences in QSM could reflect changes in these processes. Methods We scanned 83 patients with first-episode psychosis and 64 healthy subjects. We reassessed 22 patients and 21 control subjects after 3 months. Mean susceptibility was measured in 6 deep-brain nuclei. Using linear mixed models, we analyzed the effect of case-control differences, region, age, gender, volume, framewise displacement (FD), treatment duration, dose, laterality, session, and psychotic symptoms on QSM. Results Patients showed a significant susceptibility reduction in the putamen and globus pallidus externa (GPe). Patients also showed a significant R2* reduction in GPe. Age, gender, FD, session, group, and region are significant predictor variables for QSM. Dose, treatment duration, and volume were not predictor variables of QSM. Conclusions Reduction in QSM and R2* suggests a decreased iron concentration in the GPe of patients. Susceptibility reduction in putamen cannot be associated with iron changes. Since changes observed in putamen and GPe were not associated with symptoms, dose, and treatment duration, we hypothesize that susceptibility may be a trait marker rather than a state marker, but this must be verified with long-term studies.
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    Transitions between human functional brain networks reveal complex, cost-efficient and behaviorally-relevant temporal paths
    (2020) Ramírez Mahaluf, J. P.; Medel Sierralta, Vicente; Tepper, Angeles; Alliende, L. M.; Sato, J. R.; Ossandón, Tomás; Crossley, Nicolás